syntace X-12 is slight different from most 142x12 frame droputs, the head is sferic, while most are plane
I don't know how tune is
I hope superstar make them (like 135x12), they would be light and cheap

The 142 X-12 is a separate standard from Shimano 142. X-12 uses a rounded seat for the bolt head on the left side. Shimano uses flat. Hubs are the same for both, but you have to buy the correct bolt for your frame.

Are both 142s the same thread or is shimano the bigger thread like Maxle 135? I go a DT X12 axle for my Scott but then found that my dropout has flat face. I replaced the axle's conical washer with a flat one and all is good. Is my frame the Shimano standard?

The Syntace bolt on axle is very nice. Fit my Stumpjumper frame perfectly (tucked right into the dropout, like it was made for it). Not as pretty as the Specialized/DT Swiss lever axle that it replaced, but almost an ounce lighter and the simplicity is beautiful.

Are both 142s the same thread or is shimano the bigger thread like Maxle 135? I go a DT X12 axle for my Scott but then found that my dropout has flat face. I replaced the axle's conical washer with a flat one and all is good. Is my frame the Shimano standard?

I have a scott genius LT with 142x12, flat interface, so shimano standard
And it came with the DT 142x12 axle (also flat), with a very good weight, 62g, with RWS lever system.

The threading of the nut should be the same as the syntace x-12, but you need to measure the length of your existing shimano axle to see if the syntace will be long enough. Also, as other's have stated, the X12 system uses a conical washer, which you'll probably have to replace with a flat washer of some type.

But post up some pics of your dropouts to paint a better picture of what you have. I recently fitted an X12 axle to my Nomad and it was shorter than the RWS axle that came with the frame, but there was enough thread engagement to work. I also had to ditch the conical washer to use it and make a new flat washer in it's place.

This thread shows the exact frame that I have. It appears as though the Shimano 142x12 axle is not compatible with the Syntace X12 system as they have different threads. Can anybody confirm this? I don't speak Italian.

This thread shows the exact frame that I have. It appears as though the Shimano 142x12 axle is not compatible with the Syntace X12 system as they have different threads. Can anybody confirm this? I don't speak Italian.

He shows a photo of 2 axles. The bottom one is a Syntace and it's thread look like a DT. The top one with the cam lever looks to have courser threads, like a Maxle.